Plant & Animal Genome IX Conference

Poster: Large Insert Libraries, Gene Isolation, Etc.
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MAP-BASED CLONING OF THE HERO RESISTANCE GENE CONFERRING RESISTANCE TO POTATO CYST NEMATODES

¹ Institute for Plant Genetics, Corrensstr. 3, D-06466 Gatersleben, Germany

² Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA, United Kingdom

The Hero resistance gene confers resistance to all known pathotypes of Globodera rostochiensis and partial resistance to Globodera pallida. The gene has been mapped to the short arm of tomato chromosome 4. A high resolution genetic map of the region was constructed and overlapping clones were isolated for a region of 180 kb containing the Hero gene. Cosegregating with the Hero gene, we identified a gene family with homology to other disease resistance genes with an NBS and leucine-rich repeats. A detailed characterization of this gene family and sequencing of a 150 kb region revealed 14 highly related members. The NBS-LRR genes showed up to 98% similarity and 8 of these genes appear to be intact. At least four of the genes are expressed in resistant as well as susceptible lines and transcript levels are generally higher in roots than in leaves. Using two recombinants within the gene family, it was possible to delimit the gene conferring the actual resistance to three members. Transformation of the three genes individually into a susceptible tomato variety identified one single gene conferring the actual Hero resistance. A detailed structural analysis revealed that the Hero gene encodes a protein of 1302 amino acids. Interestingly, the most closely related tomato gene to Hero is the Mi gene which confers resistance to root knot nematodes.